1. Field of the Invention
This invention relates to a bicycle, more particularly to a transmission assembly for an electrically powered bicycle, which has an electrical transmission unit that is provided with a planetary gear device.
2. Description of the Related Art
In a conventional electrically powered bicycle, the rotation of a motor shaft is transferred to a front sprocket by means of an electrical transmission unit which has a relatively large number of parts, thereby resulting in greater power loss and increased volume.
Therefore, the object of this invention is to provide a transmission assembly for an electrically powered bicycle, which has an electrical transmission unit that is provided with a planetary gear device and an auxiliary speed-reducing device so as to reduce the volume and the power loss of the assembly.
According to this invention, a transmission assembly for an electrically powered bicycle has a manual transmission unit and an electrical transmission unit. The electrical transmission unit includes a planetary gear device for transferring rotation of a motor shaft of a motor to a front sprocket.